1. Field of the Invention
This invention relates to a novel peptide.
The peptide provided by this invention is easily immobilized on a carrier and enabled to effect specific adsorption of a human antibody to a nicotinic acetylcholine receptor. The peptide of this invention is therefore useful for the therapy of myasthenia gravis which is held to have its main symptoms in the disorder caused in neuromuscular transmission by the autoantibody to the nicotinic acetylcholine receptor present on the post-synaptic membrane in the neuromuscular junctions
2. Prior Art Statement
It is reported in "Nature", vol. 299, pages 793-797 (1982) that the .alpha.-subunit precursor of the nicotinic acetylcholine receptor obtained from the electric organ of Torpedo californica, one species of electric ray, is composed of 461 amino acids and that the primary structure of the precursor has been successfully elucidated. According to this report, the amino acid sequence at the 183rd to 200th positions in the primary structure of the .alpha.-subunit precursor is represented by the formula -Gly-Trp-Lys-His-Trp-Val-Tyr-Tyr-Thr-Cys-Cys-Pro-Asp-Thr-Pro-Tyr-Leu-Asp-. In Proceedings of the National Academy of Sciences of the United States of America, Vol. 84, pages 3633-3637 (1987), it is reported that a peptide corresponding to the amino acid sequence at the l82nd to l98th position in the primary structure of the .alpha.-subunit of the nicotinic acetylcholine receptor obtained from the electric organ of Torpedo californica has been synthesized and that an adsorbent formed by immobilizing this peptide on an agarose type carrier (CNBr-activated Sepharose CL-4B) has an ability to bind itself with a mouse antibody and a rabbit antibody to the nicotinic acetylcholine receptor. In Biochemical and Biophysical Research Communications, Vol. 135, pages 82-89 (1986), it is reported that the .alpha.-subunit of the nicotinic acetylcholine receptor obtained from Torpedo californica, on hydrolysis with a protease, produces a fragment possessing a molecular weight of 18 kilo-daltons and presumed to correspond to the amino acid sequence at the 153rd to 350th positions in the primary structure of the .alpha.-subunit and that this fragment has an ability to bind itself with .alpha.-bungarotoxin and a mouse monoclonal antibody against the ligand binding site of the nicotinic acetylcholine receptor.
For the therapy of myasthenia gravis it is desired to establish a method for effective removal of the human autoantibody to the nicotinic acetylcholine receptor which is thought to be the main cause of myasthenia gravis.